Plot markers around the perimeter of a shape

I have the perimeter of a tumour plotted over a dicom image (Drawn with impoly). I want to place a user inputted number of markers (I know how to get a user to input a number) equally spaced around this perimeter. An example to visualise it is perhaps like plotting north, east, south, west, etc. on a circle. I can't find a suitable function in the help so perhaps somebody on here has solved a similar problem.

If I could get a list of x, y coordinates in clockwise order around my shape I could then select an nth pair of coordinates to place a marker on eg. plot(x, y, 1:50:end)?

Thank you.

Answer 1

[Thorsten]

Draw sample contour (e.g, a circle)

   th = linspace(0, 2*pi);
   x = cos(th); y = sin(th);
   plot(x, y, 'k-')

Draw N equally spaced points on the contour

   N = 10;
   ind = round(1:length(th)/N:length(th));
   hold on
   plot(x(ind), y(ind), 'r.')